JP2001078458A - Single phase rectifier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve power factor of an AC input by controlling the on/off condition of a both-way switch to cause the double-throw switch and rectifier to operate as a voltage boosting chopper circuit for single phase AC input. SOLUTION: For in a 100 V system with an AC input voltage, a change-over switch 11 closes in the side of front contact 11a, to operate a rectifying circuit 16 as a single-phase double voltage rectifying circuit. However, when the AC input voltage is 200 V system, the change-over switch 11 is closed in the side of back contact 11b, in order to operate the rectifying circuit 16 as a single- phase full-wave rectifying circuit. A reactor 2 controls, for the AC input power supply 1, the on/off operation of the semiconductor double-throw switch 15 with a controller 17 to realize the voltage boosting chopper operation with four diodes 7, 8, 12, 13 and capacitors 9, 10 forming a diode bridge as the rectifier.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single-phase rectifier for switching between a single-phase full-wave rectifier circuit and a single-phase voltage doubler rectifier circuit.

[0002]

2. Description of the Related Art One of the conventional single-phase rectifiers is to switch a single-phase full-wave rectifier circuit and a single-phase voltage doubler rectifier circuit according to the voltage of a single-phase alternating current to provide a constant DC voltage. There is something to gain.

This single-phase rectifier has a single-phase AC input of 10
In the case of 0V system, it is switched to use a single-phase double voltage rectifier circuit, and in the case of a single-phase AC input of 200V system, it is switched to use a single-phase full-wave rectifier circuit, and the voltage is regulated to about 300V. This is a device for obtaining a DC voltage.

However, in this single-phase rectifier, the power factor of the AC input cannot be improved, and it is difficult to obtain a DC output of a constant voltage.

In order to improve the AC input power factor and to make the DC output constant voltage, a power factor improving circuit using a step-up chopper circuit is generally used.

FIG. 2 shows an example of a conventional single-phase full-wave rectification system for improving the power factor of an AC input.

The single-phase full-wave rectifier 200 shown in FIG.
The diodes 22, 23, 24, and 25 form a diode bridge, and a reactor 2 connected in series to the diode bridge.
Numeral 6 performs a step-up chopper operation of storing energy when the semiconductor switch 27 is turned on and discharging the energy stored in the reactor 26 to the capacitor 29 via the diode 28 when the semiconductor switch 27 is turned off.

The semiconductor switch 27 is, for example, a transistor, and its ON / OFF signal is controlled by a control circuit (not shown) so that the AC input current matches the AC input voltage.

In the step-up operation of the circuit of FIG. 2, when the AC input voltage is 100 V or 200 V,
To keep the DC voltage constant at about 300 V, the input voltage of the 100 V system becomes twice as high as that of the 200 V system input.

[0010]

However, in such a conventional single-phase rectifier, the AC input power factor improving circuit controls the instantaneous value of the AC input current with respect to the AC input voltage to improve the power factor. Is being planned. For this reason, the effect of power factor improvement is greater as the boost ratio is larger.However, when the boost ratio fluctuates greatly, crossover distortion occurs in the AC input current when the boost ratio is reduced, and the input power factor is improved. There was a problem that it could not be performed sufficiently.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problem. In a case where an AC input voltage fluctuation range is large, a single-phase full-wave rectifier circuit and a single-phase voltage doubler rectifier circuit are switched to provide a power factor of an AC input. It is an object of the present invention to provide a single-phase rectifier capable of making improvements.

[0012]

According to a first aspect of the present invention, there is provided a single-phase rectifier, comprising: a reactor (for example, a reactor 2) connected in series to a single-phase AC input stage; A bidirectional switch (for example, a semiconductor bidirectional switch 15) connected in parallel to a single-phase full-wave rectifier circuit connected in parallel to the single-phase AC input stage at the subsequent stage of the bidirectional switch. (For example, a rectifier 16) having a rectifier and a single-phase voltage doubler, and a changeover switch for selectively switching between a single-phase full-wave rectifier circuit and a single-phase voltage doubler rectifier in the rectifier. (E.g., a changeover switch 11), and when the rectifier is switched to a single-phase full-wave rectifier circuit or a single-phase voltage doubler rectifier circuit by this changeover switch, the bidirectional switch is turned on / off. Bidirectional switch and the commutation control unit to operate as a step-up chopper circuit device to the single-phase AC input (e.g., controller 17) and is characterized by having a.

According to the single-phase rectifier of the first aspect, in the single-phase input rectifier having a large variation range of the AC input voltage, the single-phase full-wave rectifier circuit and the single-phase double voltage rectifier circuit are switched and used. A step-up chopper circuit using a rectifier and a bidirectional switch capable of on / off control on the AC input stage side is added.

Therefore, the DC output voltage can be made constant, and control can be performed without greatly changing the control gain of the step-up chopper.

As a result, the power factor of the AC input can be improved, and the crossover distortion of the AC input current can be reduced.

[0016]

Embodiments of the present invention will be described below in detail with reference to FIG. FIG. 1 is a diagram showing an embodiment of a single-phase rectifier to which the present invention is applied.

First, the configuration will be described. FIG. 1 is a diagram illustrating a circuit configuration of a single-phase rectifier according to an embodiment of the present invention.

In the single-phase rectifier 100 of FIG. 1, one end of a reactor 2 is connected in series with one line of a single-phase AC input, and a control unit 17 is connected between the other end and the other line of the single-phase AC input. A bidirectional switch, for example, a semiconductor bidirectional switch 15 capable of controlling on / off between AC voltages is connected.

This semiconductor bidirectional switch 15 is composed of two transistors 3 and 4 and two diodes 5 and 6. The anode terminals of the diodes 5 and 6 are connected to the emitters of the transistors 3 and 4, respectively. The cathode terminals of the diodes 5 and 6 are connected to the diodes 5 and 6 in anti-parallel with the two sets of transistors 3 and 4 connected to the collectors of the transistors 3 and 4, respectively. The bases are connected to each other, and the base signal of the transistor is a single system.

A connection point between the reactor 2 and the semiconductor bidirectional switch 15 is connected to an intermediate point of a first diode arm in which two diodes 7 and 8 are connected in series, and the other end of the semiconductor bidirectional switch 15 is connected to a front contact. It is connected to a common point of a changeover switch 11 having a back contact 11a and a back contact 11b.

When the rectifier circuit 16 operates as a single-phase full-wave rectifier circuit, the changeover switch 11 connects the connection terminal of the back contact 11a to two diodes 12, 13 different from the first diode arm. Is connected to the middle point of the second diode arm connected in series, and the rectifier circuit 16 is a single-phase voltage doubler rectifier circuit, the front contact 11
The connection terminal b is connected to an intermediate point between the two capacitors 9 and 10 connected in series.

The cathode terminals of the two diodes 7 and 12 are connected to one end of the capacitor 9 connected in series, which is not the intermediate point, to serve as a positive terminal for DC output. The anode terminals of the other two diodes 8 and 13 are connected in series. Capacitor 1
One end other than the midpoint of 0 is connected to form a DC output negative terminal.

The control unit 17 includes a semiconductor bidirectional switch 15
Is controlled so that the AC input current matches the AC input voltage.

Next, the operation of the present embodiment will be described separately for the case where the AC input voltage of the single-phase rectifier is a 100 V system and a 200 V system.

When the AC input voltage is of a 100 V system, the changeover switch 11 is closed to the front contact 11a in order to operate the rectifier circuit 16 as a single-phase voltage doubler rectifier circuit.

Reactor 2 is connected to AC input power supply 1 by 2
By controlling the on / off operation of the semiconductor bidirectional switch 15 including the transistors 3 and 4 and the two diodes 5 and 6 by the control unit 17, the boost chopper operation is performed by the diodes 7 and 8 and the capacitors 9 and 10. .

When an AC input current flows from the reactor 2 to the AC input power supply 1 via the load resistor 14 and returns to the AC input power supply 1 (hereinafter referred to as “forward direction”), the semiconductor bidirectional switch 15
Is turned on, a current flows from the AC input power supply 1 to the AC input power supply 1 through the reactor 2, the transistor 3, and the diode 6. When the semiconductor bidirectional switch 15 is turned off, the energy stored in the reactor 2 returns from the reactor 2 to the reactor 2 through the diode 7, the capacitor 9, the changeover switch 11, and the AC input power supply 1.

When the AC input current flows from the load resistor 14 to the AC input power supply 1 via the reactor 2 and returns to the AC input power supply 1 (hereinafter referred to as “reverse direction”), the semiconductor bidirectional switch 15
Is turned on, current flows from the AC input power supply 1 through the transistor 4, the diode 5, and the reactor 2 to the AC input power supply 1.
Flows to When the semiconductor bidirectional switch 15 is turned off, the energy stored in the reactor 2 returns from the reactor 2 to the reactor 2 through the AC input power supply 1, the changeover switch 11, the capacitor 10, and the diode 8.

On the other hand, when the AC input voltage is a 200 V system, the changeover switch 11 is closed to the back contact 11b in order to operate the rectifier circuit 16 as a single-phase full-wave rectifier circuit.

The reactor 2 is connected to the AC input power supply 1 by 2
The control unit 17 controls the on / off operation of a semiconductor bidirectional switch 15 including two transistors 3 and 4 and two diodes 5 and 6 to form four diodes 7, 8, 12, and 13 and a capacitor. The boost chopper operation is performed by 9 and 10.

When the AC input current flows in the forward direction, when the semiconductor bidirectional switch 15 is turned on, the current is supplied from the AC input power supply 1 to the reactor 2, the transistor 3, the diode 6
Through the AC input power supply 1. When the semiconductor bidirectional switch 15 is turned off, the energy stored in the reactor 2 returns from the reactor 2 to the reactor 2 through the diodes 7, the capacitors 9, 10, the diode 13, the changeover switch 11, and the AC input power supply 1.

When the AC input current flows in the reverse direction, when the semiconductor bidirectional switch 15 is turned on, the current flows from the AC input power supply 1 to the transistor 4, the diode 5, and the reactor 2.
Through the AC input power supply 1. When the semiconductor bidirectional switch 15 is turned off, the energy stored in the reactor 2 returns from the reactor 2 to the reactor 2 through the AC input power supply 1, the changeover switch 11, the diode 12, the capacitors 9, 10, and the diode 8.

As described above, according to the single-phase rectifier 100 of the embodiment of the present invention, when the fluctuation range of the AC input voltage is large, the rectifier circuit 16 is changed to the single-phase full-wave rectifier circuit and the single-phase rectifier circuit. By switching and using the voltage rectifier circuit and adding a boost chopper circuit using the semiconductor bidirectional switch 15 to the AC input stage side, it is possible to make the DC output voltage constant. Further, the control can be performed without greatly changing the control gain of the boost chopper, and the power factor of the AC input can be improved. Accordingly, it is possible to reduce the crossover distortion of the AC input current.

[0034]

According to the single-phase rectifier of the present invention, in the single-phase input rectifier having a large fluctuation range of the AC input voltage,
By adding a rectifier that switches and uses a single-phase full-wave rectifier circuit and a single-phase voltage doubler rectifier circuit, and a step-up chopper circuit that uses a bidirectional switch that can be turned on / off on the AC input stage side, The output voltage can be made constant. Further, the control can be performed without greatly changing the control gain of the boost chopper, and the power factor of the AC input can be improved. Accordingly, it is possible to reduce the crossover distortion of the AC input current.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a circuit configuration of a single-phase rectifier according to an embodiment of the present invention.

FIG. 2 is a diagram showing a circuit configuration of a conventional single-phase full-wave rectifier.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 AC input power supply 2 Reactor 3 and 4 Transistor 5-8,12,13 Diode 9,10 Capacitor 11 Changeover switch 14 Load resistance 15 Semiconductor bidirectional switch 16 Rectifier circuit 17 Control part

Claims (1)

[Claims] 1. A reactor connected in series to a single-phase AC input stage, a bi-directional switch connected in parallel to the single-phase AC input stage at a stage subsequent to the reactor, and a bi-directional switch connected to the single-phase AC input stage at a stage subsequent to the bi-directional switch. A rectifier connected in parallel to the single-phase AC input stage and having a single-phase full-wave rectifier circuit and a single-phase voltage doubler rectifier circuit; and a single-phase full-wave rectifier circuit and single-phase doubler voltage rectifier in the rectifier. A changeover switch for selectively switching each circuit configuration of the circuit, and when the rectifier is switched to a single-phase full-wave rectifier circuit or a single-phase voltage doubler rectifier circuit by the changeover switch,
A single-phase rectifier comprising: a control unit that controls on / off of the bidirectional switch to operate the bidirectional switch and the rectifier as a boost chopper circuit with respect to the single-phase AC input. apparatus.